diff --git a/docs/development.md b/docs/development.md
index 08d4d93..a51b7dc 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -10,10 +10,9 @@ How to work on theme-toggle in a clone. The [contributing guide](contributing.md
 mise install
 pnpm install
 playwright install chromium   # the browser the tests run in
-lefthook install              # the git hooks in lefthook.yml
 ```
 
-pnpm doesn't run lefthook's own install script, so the hooks need `lefthook install` once. After changing a version in `mise.toml`, run `mise lock` and commit both files.
+`pnpm install` also installs the git hooks in `lefthook.yml`, because `pnpm-workspace.yaml` allows lefthook's install script. After changing a version in `mise.toml`, run `mise lock` and commit both files.
 
 ## Tasks
 
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 8e6e557..882cd32 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -1,3 +1,10 @@
+allowBuilds:
+  lefthook: true
+
+# lefthook's postinstall installs the git hooks, so it has to run on every install:
+# with the side-effects cache on, a lefthook already built for another project skips it.
+sideEffectsCache: false
+
 # Supply-chain cooldown: malicious releases are usually pulled within 24h; pattern excludes need pnpm >= 10.17.
 minimumReleaseAge: 1440
 minimumReleaseAgeExclude: